1. Field of the Invention
The present invention concerns hydraulically controlled clutch release bearings for a diaphragm clutch, notably for a motor vehicle, having a fixed portion comprising an inner support tube and an outer body concentric therewith, defining a blind annular cavity of axial orientation capable of being supplied with fluid and inside which is mounted an axially movable tubular piston.
2. Description of the Prior Art
Such a bearing is described for example in the document FR-A-2 692 950. In this document, the inner tube projects axially in relation to the outer body.
The piston carries at its front end a drive member capable of acting on the diaphragm of the clutch.
This bearing can be supplied by a fluid of the gaseous or liquid type and this is the reason why it is usually referred to as a hydraulically controlled clutch release bearing.
There is a problem with this type of bearing as impurities can enter the cavity defining with the piston a control chamber of variable volume.
The object of the present invention is to overcome this drawback in a simple and economical manner.